just thot id mention to u ,,that gatekeeper who apparently works where they cut the ties all the time.,,is recommending an fast full chisel chain..
its not clear ,,but i suspect they are cutting new ties.. the main problem i see with them .... has to do with the railway braking system. [if it hasnt changed]
they use goodly amounts of sand dropped on the track to help the metal against metal braking work better..
if i was doing this on used ties i think and good pressure washing ,,making sure to drive this imbedded sand out rather than deeper into the wood fiber mite help save a lot of sharpening..jm take on it . good luck.
ps also u mite want to cut from the side that was down ,,when they were in use..